EMG-5 Genisis
The Part 103 rule really challenges the designer. There were many designs and even a few attempts at construction of other aircraft that preceded this design. At a certain point, around 2009, we had made a decision to press forward with research and development surrounding an electric powered aircraft. We had done extensive research on available motors as well as battery and controller technology that we could take advantage of. The aircraft design started to show some of the difficulties as we proceeded down this path.

Electric motor glider version 1 or as we called it: EMG – 1.

emg1
The Genesis of this aircraft design is a cumulative effort over many years to develop an aircraft that both could be powered by electric motors and would fit into FAR part 103.
Weight from the very beginning was one of the biggest obstacles to overcome. The amount of wing area necessary to have a gross weight in the neighborhood of 550 pounds was nearly 130 ft.² to 150 ft.², depending on the airfoil. High lift airfoils required less area, but they generate significantly more drag. More appropriately designed low drag airfoils require greater wing area increasing the weight. The EMG – 1 was a simplified design with the pilot in a prone position in order to reduce total drag using a candle levered D tube constructions spar with a sailcloth wing covering. Initially, the design had a simplified landing gear, and eventually, in an attempt to reduce drag, a retractable gear system. Every design change that was made sacrificed one aspect for another. The design was starting to take shape. The basic concept validated. The cost of construction was acceptable. The ability to tow the aircraft was established. Weight and balance in the preliminary design was acceptable. Visibility was acceptable. A wing fold system could be incorporated
emg1.1
In our focus group discussions there were concerns about the prone position of the pilot. Several design options were considered for getting in and out of the aircraft in a prone position and this proven to be the final demise of this particular design. The 4130 chrome Molly steel tube fuselage just did not allow for easy egress.The concept seemed promising. Yet we shelved the aircraft design to look at other options. We took what we had learned from this exercise and incorporate the good ideas into the next concept. Along came the second version
emg2.0

Electric motor glider version 2. (EMG – 2)

We began designing an aircraft with the pilot in the reclined seated position. Even on the initial drawings it was evident that this presented some real difficulties with related structural requirements regarding the pilot weight which was approximately 1/2 of the total aircraft gross weight. Center of gravity issues made it very difficult to position the pilot in a fashion that would allow for a main spar carried through without interfering with the pilot’s mobility and once again even egress from the aircraft. This design also presented problems with visibility, mounting of the engines and all of the wasted space behind the pilot increasing weight and complexity to the point that we became aware that we needed even a better concept to push forward.
emg-3

Electric motor glider version 3. (EMG – 3)

After doodling on paper with multitude of designs, we came up with an idea that looked like it would be worthwhile pursuing. We completed various calculations for all of the particulars of the aircraft to see where it would lead us. The new design concept was very sexy looking, with a low drag profile. The engines could be mounted aft of the pilot along with the batteries in order to deal with the forward center of gravity issue with the pilot, along with mounting the BRS after the pilot in unused space. But as the analysis continued we found the requirements for the structure supporting the weight of the pilot was eating into our total empty weight. the ability to provide any degree of crash protection up front was a significant weight penalty. Additionally the pilot position forward of the main load carrying spar require that the engines be mounted aft of the center of gravity. The design was very cool looking and from an aesthetic standpoint very salable. However the empty weight for aircraft of this design was considerably greater than what part 103 would allow. Wing area alone for this type aircraft would have to be increased to nearly 150 ft.² with the tail boom been extended aft considerably. The compromise to expose the pilot significantly in a crash configuration in order to save weight is a common strategy used within the experimental aircraft world, however it was a compromise we all seemed unwilling to live with. As a result more design configurations were developed and considered.
emg3.1
We already had a design that would require a canopy that would open from the front and a seated position that, while it was relatively low drag, was difficult to keep the weight down and provide any degree of crash protection. The option for a boom fuselage reduced both the construction cost and complexity while keeping the weight relatively low but we were still faced with complex issues combining both composites and aluminum and steel structures that would allow for a weight that was acceptable. In the final analysis even with virtually no crash protection up front and an extremely vulnerable pilot configuration the ability to build the aircraft as a part 103 aircraft fell short by nearly 30% of our design goal. The configuration of a pilot seated in the supline position in an aircraft where the pilot weight equals the aircraft empty weight seen virtually impossible. Several variations on the theme were generated including building the spar on both top and bottom of the pilot were derived all designs were falling short of part 103 requirements.

Electric motor glider version 4. (EMG – 4)

emg-4
In order to reduce the total weight of the aircraft, we extend the simple boom tube all the way to the front using it as the main load carrying member. this would enhance the crash protection feature and reduce the total structural requirement around the pilot. We found now that having the boom under the pilot’s seat raised the top of the fuselage to such a great extent that we were now suffering an increased frontal area that needed to be addressed. We had been working on wing designs and felt that are basic wing idea was acceptable.the wing fold mechanism looked doable. The amount of wing area was still a bit of a challenge. The overall weight of the aircraft would really reduce the amount of battery capacity. The canopy/windscreen was going to be a significant investment. The egress problem would involve significant complex components and add to the weight. The concept of having an aircraft that could be towed, trailered and stored at home has always been one of the concepts that pilots desire. It was this basic design that led eventually into what is now the EMG-5. Actually the EMG-5 was also shelfed for a period of time trying to resolve the total weight issue primarily as a result of the large wing area. We went on to explore several other variations on the aircraft before we hit upon the idea of using thrust vectoring motors. It was the thrust vectoring motors concept which looked like it could bring the wing area into the realm of possibility for a part 103 aircraft.

EMG – Electric motor glider version 5. (EMG – 5)

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